4G Americas Carrier Aggregation_FINALv1 0 (2)

CA has also been designed to be a future-proof technology, with great potential into and beyond Release12. By extending aggregation to more carriers and enabling aggregation of additional licensed spectrum,CA will play a key role in enabling both IMT-Advanced and the use of emerging spectrum allocations.There also will be multiple and varied deployments of CA tailored to operators’ specific requirements.However, this seemingly simple concept will continue to stretch the realm of network and deviceimplementations. Strong collaboration across the industry for further innovations, evolutions andoptimization will drive CA as a mainstream technology. In particular, operators are advised to carry outconsultations with their RAN infrastructure vendors, device suppliers and chipset manufacturers whendeveloping their CA implementation plans.2. INTRODUCTION [1]The first version of LTE was completed in March 2009 as part of Third Generation Partnership Program(3GPP) Rel-8. LTE is based on a flat radio access network architecture without a centralized networkcomponent. LTE offers flexible bandwidth options ranging from 1.4 to 20 MHz using orthogonalfrequency-division multiple access (OFDMA) in the downlink and single-carrier, frequency-divisionmultiple access (SC-FDMA) in the uplink.In March 2008, 3GPP started a new study item to further develop LTE toward LTE-Advanced by targetingthe IMT-Advanced requirements as defined by the International Telecommunication Union (ITU). TheLTE-Advanced study item was closed in March 2010. The outcome was a set of new radio features,which are currently being standardized to become part of LTE-Advanced. CA is one of the main featuresof LTE-Advanced in Rel-10 for meeting the peak data rate requirements of IMT-Advanced: 3 Gbps DLand 1.5 Gbps UL 1 . With CA, users gain access to a total bandwidth of up to 100 MHz in order to meet theIMT-Advanced requirements. The system bandwidth may be contiguous, or composed of several noncontiguousbandwidth chunks that are aggregated. CA is designed to be backward compatible, meaningthat legacy Rel-8 and Rel-9 users should be able to coexist with LTE-Advanced on at least part of thetotal bandwidth.This white paper presents a summary of CA technology ranging from the basic concepts to futureevolutions. It also provides an overview of supported CA configurations and combinations specified in3GPP, CA control mechanisms, common CA deployment scenarios, specific use cases, deviceimplementations and performance impacts. The paper also summarizes future enhancements that willcontinue to drive the evolution of CA technology and deployment as a mainstream technology. A glossarysection at the end defines the acronyms and terms used throughout this paper.3. GLOBAL MARKET TRENDS, MILESTONES IN CARRIER AGGREGATION(CA)Mobile operators continue to seek efficient and cost-effective solutions to support the high demand fordata and next-generation services. Spectrum continues to be a limiting factor. A majority of operatorshave spectrum allocations of less than 20 MHz contiguous spectrum or have multiple bands or noncontiguousspectrum blocks. As a solution, operators worldwide are adopting CA technology, which isone of the main features of LTE-Advanced in Rel-10. Over the long term, CA will enable operators tomeet the peak requirements of IMT-Advanced: 3 Gbps DL and 1.5 Gbps UL.1 See http://www.3gpp.org/technologies/keywords-acronyms/97-lte-advanced4G Americas LTE Carrier Aggregation October 2014 5